Carbohydrate Stains - PAS, Alcian Blue, Toluidine Blue (Wk 7)

Question 1

This is the property of certain dyes which stain different colours depending on what tissue element they are attached to.

Answer 1

METACHROMASIA

Question 2

Schiff’s effectiveness can be tested by adding a few drops to ________

Answer 2

formalin

Question 3

This is the term for alcohol groups on adjacent carbons in a sugar molecule?

Answer 3

VICINAL DIOLS

Question 4

This is what the D in PAS + D stands for.

Answer 4

DIASTASE

Question 5

This value is one measurement of acid strength and is useful in determining at which pH anionic components will be ionized.

Answer 5

pKa

Question 6

Schiff’s reagent binds to this reactive group

Answer 6

ALDEHYDES

Question 7

3 important factors in metachromatic staining

Answer 7

• pH
• Water (dehydration will destroy metachromatic staining)
• Spacing between anionic groups (0.3-0.5 nm spacing between groups; otherwise won’t stain)

Question 8

Your spit contains this enzyme.

Answer 8

AMYLASE

Question 9

This is one of the major types of mucosubstances and is found in connective tissues?

Answer 9

PROTEOGLYCANS

Question 10

2 components in Mucicarmine?

Answer 10

aluminum + carmine

Question 11

This is the name for an anionic group which will stain red-purple with Toluidine blue.

Answer 11

CHROMOTROPE

Question 12

Schiff’s reagent may revert back to pararosaniline which is what colour?

Answer 12

pink

Question 13

3 alternate stains for Alcian blue

Answer 13

• Mucicarmine
• Colloidal iron
• Lectins

Question 14

The carbohydrate component of a proteoglycan is called?

Answer 14

Glycosaminoglycan

Question 15

Glycoproteins can be removed by using..?

Answer 15

Neuraminidase

Question 16

Why must Alcian blue/PAS be done in a particular order, and what that order is?

Answer 16

Alcian before PAS

Schiff’s will introduce sulphonic acid groups = false positives if stained w/ Alcian

Question 17

Chromophore in pararosaniline?

Answer 17

Quinoid ring

Question 18

When this kind of a chemical group is ionized it can be stained with Alcian blue at pH 2.5 but not at pH 1.0?

Answer 18

CARBOXYLIC ACID

Question 19

2 types of carbohydrates that stain with Alcian Blue

Answer 19

Proteoglycans

Acid glycoproteins (NOT neutral)

Question 20

The name for HIO4

Answer 20

PERIODIC ACID

Question 21

This is the most common dye used to demonstrate amyloid.

Answer 21

CONGRO RED

Question 22

Proteoglycans can be removed by using..?

Answer 22

Hyaluronidase

Question 23

These mucosubstances are considered to be epithelial mucins.

Answer 23

GLYCOPROTEINS

Question 24

Why is pararosaniline a PSEUDOLEUCO dye?

Answer 24

Colourless (due to addition of SO3- to chromophore) and colour is re-established in presence of aldehydes

Not a true leuco dye b/c doesn’t involve redox rxn

Question 25

Why is pararosaniline preferred over basic fuchsin to make Schiff's reagent

Answer 25

Basic fuchsin is a MIXTURE of dyes Pararosaniline is a SINGLE dye (better specificity)

Question 26

General description of dyes which can be used to demonstrate acid mucins and other negatively charged components?

Answer 26

CATIONIC

Question 27

This is the pH at which only sulphated proteoglycans will stain.

Answer 27

pH 1.0

Question 28

Modern Schiff's reagent is made from this single dye

Answer 28

Pararosaniline

Question 29

Repetitive anionic groups responsible for metachromatic staining

Answer 29

Chromotropes

Question 30

Purpose of staining at pH 1.0 and 2.5 for Alcian blue?

Answer 30

Differentiate between sulphate and carboxylated mucins (via none/increase in staining intensity) COOH only stains at 2.5

Question 31

This dye will specifically demonstrate Cryptococcus neoformans.

Answer 31

MUCICARMINE

Question 32

This simple sugar is rarely seen in human tissues due to its solubility.

Answer 32

GLUCOSE

Question 33

What functional group gets attached to carbohydrates after the addition of Schiff's reagent?

Answer 33

SO3H

Question 34

PAS is an example of a staining method that works via __________ bonding

Answer 34

covalent

Question 35

2 potential false positives in PAS due to the oxidation step?

Answer 35

- Glutaraldehyde-fixed tissues | - Some lipids

Question 36

The liver would be one place to find this mucosubstance.

Answer 36

GLYCOGEN

Question 37

PAS stain will demonstrate neutral mucins located in ______________ of liver

Answer 37

portal triads

Question 38

This is a mucosubstance which is often linked to proteins in glycoproteins?

Answer 38

SIALIC ACID

Question 39

Used to detect aldehydes?

Answer 39

SCHIFFS REAGENT

Question 40

How is the chromophore in pararosaniline modified?

Answer 40

Destroyed by addition of SO3- to form colourless solution

Question 41

4 main PAS(+) substances

Answer 41

- Glycogen - Neutral glycoproteins (stomach) - Neutral glycoproteins (SI) - Basement membranes

Question 42

Why don't proteoglycans stain PAS-positive?

Answer 42

Periodate ion (HIO4-) is repelled by COO- and SO3- parts of proteoglycan = no oxidation

Question 43

Oxidizing agent in PAS stain

Answer 43

Periodic acid

Question 44

This is a term for anisotrophic substances.

Answer 44

BIREFRINGENT